Emerging additive manufacturing processes are enabling a new perspective on the design of mechanical systems. Additive manufacturing, like nature, builds structures layer by layer rather than by removal of material. This approach to manufacturing enables the synthesis of components and systems that have previously been impossible. The first additive processing systems based on stereolithography (3D printing) were introduced in the late 1980's. Today, there are many different approaches, including Stereolithography (SLA), Selective Layer Sintering (SLS), Fused Deposition Modeling (FDM), Solid Ground Curing (SGC), and Laminated Object Manufacturing (LOM) among others, to construct a part layer by layer. The primary advantage of additive manufacturing is that complexity has little incremental cost. Unlike traditional machining practices which begins with a block of material and then removes material from that block to create a part, additive manufacturing decomposes the final part into layers and builds the part layer by layer. Parts can be made with voids (reducing weight and material usage) and additional complexity does not waste material or cost additional machining time.
The earliest additive manufacturing systems focused on polymers and plastics. Today, there are many emerging metal based additive manufacturing systems. Direct manufacturing technologies (E-Beam, Laser and Ultrasonic deposition) enables manufacturing using conventional metal alloys. These manufacturing technologies radically change the types of components that can be made. It is possible to build more anthropomorphic components or incorporate lattice structures for weight reduction or selective compliance where desired. Ultrasonic additive manufacturing uses a combination of additive and subtractive techniques enabling precise machining of intricate components and channels while simultaneously merging dissimilar materials. This low temperature process enables incorporation of sensitive materials such as sensors, wires, even fiber optics directly into the structure. However, whether metal or plastic, all applications of the systems have only focused on the development of mechanical components.
Examples in the literature of various additive manufacturing technologies can be found in A. Allanic, C. Medard and P. Schaeffer, “Stereophotolithography: A Brand New Machinery,” Solid Freeform Fabrication Symposium, pp. 260-271, Austin Tx, 1992; Y. Hou, T. Zhao, C. Li and Y. Ding, “The Manufacturing of Rapid Tooling by Stereo Lithography,” Adv. Materials Research Vols. 102-104, pp. 578-582, 2010; J. Song, Y. Li, Q. Deng and D. Hu, “Rapid Prototyping Manufacturing of Silica Sand Patterns Based on Selective Laser Sintering,” Journal of Materials Processing Technology, Vol. 187-188, pp. 614-618, 2007; L. Aijun, Z. Zhuohui, W. Daoming and Y. Jinyong, “Optimization Method to Fabrication Orientation of Parts in Fused Deposition Modeling Rapid Prototyping,” Int. Conf. on Mechanic Automation and Control Engineering (MACE), pp. 416-419, 2010; X. Zhang, B. Zhou, Y. Zeng and P. Gu, “Model Layout Optimization for Solid Ground Curing Rapid Prototyping Processes,” Robotics and Computer-Integrated Manufacturing, Vol. 18, No. 1, pp. 41-51, 2002; H. Windsheimer, N. Travitzky, A. Hofenauer and P. Greil, “Laminated Object Manufacturing of Preceramic-Paper-Derived Composites,” Advanced Materials, Vol. 19, No 24, pp. 4515-4519, 2007. The disclosures of these references are hereby incorporated by reference.
The basic mechanical design and fabrication of fluid powered systems has changed little since the start of the industrial revolution. Mechanical structure, actuators (motors), electronics and sensors are all fabricated with different processes and then integrated into the final system during the assembly process. As a result, systems tend to be larger, heavier, more complex and expensive than is necessary.
Mesofluidics is an approach to miniaturization of fluidic actuation and control that enables highly integrated, energy efficient hydraulic systems. Like the human form, the miniature hydraulic actuators, along with the fluid channels, blend into the structure enabling highly integrated systems. The power and stress levels of the hydraulic systems are approximately an order of magnitude greater than human muscles, enabling strength and packaging superior to nature. Today, mesofluidic devices are manufactured using conventional fabrication practices. Recent initiatives have focused on the development of low-cost titanium materials and manufacturing techniques with a target of $10/lb for the final manufactured part. Other efforts have focused on the development of low-cost titanium powders that, when combined with additive manufacturing processes, achieve this aggressive goal. Metal additive manufacturing systems, like nature, build parts in an additive, rather than subtractive process. The integration of the actuators and fluid conduits with the structure has the advantage of compactness, ease of assembly and maintenance with increased reliability.
In 2008, sales of components exceeded $14B and sales of fluid powered systems (agriculture, construction and manufacturing equipment) was well into the hundreds of billions of dollars. Furthermore, a recent study conducted by the Oak Ridge National Laboratory (ORNL), the National Fluid Power Association (NFPA) and 23 leading fluid power manufacturers and users quantified that a) fluid powered equipment consumes between 1.95 and 2.89 Quads/year and b) the average efficiency of fluid powered equipment is 21%. A 5% improvement in average efficiency could save US industry and consumers 0.4 Quad/year, nearly $10B/year. Unlike the automotive industry, the fluid power industry has had little innovation in the past 40 years.